You roll 2 number cubes whats the probability of it being 7

You have to know all of the combinations the dice can show:

11 12 13 14 15 16

21 22 23 24 25 26

31 32 33 34 35 36

.

.

61 62 63 64 65 66

6x6=36 possible combinations handing 11 possible numbers (2,4,5,6,7,8,9,10,11,12)

As you can see some combinations repeat themselves

We can obtain number seven rolling dice in these combinations:

16 61

25 52

34 43

The probability of obtaining 7 would be how many combinations give us a 7 divided by how many possible combinations there are

P (7) = 6/36=1/6

Total number of possible outcomes = 36

Total number with sum 7 = 5

{1, 6} {2, 5} {3, 4}, {5, 2}, {6, 1}

P (sum 7) = 5/36

Answer: 5/36